Surgical instruments which include a tool assembly mounted on a distal end of a body portion of the surgical instrument for articulation are well known. Typically, such surgical instruments include articulation control mechanisms which allow an operator to remotely articulate the tool assembly in relation to the body portion of a surgical instrument to allow the operator to more easily access, operate on, and/or manipulate tissue.
Such articulating tool assemblies have become desirable, especially in the endoscopic surgical procedures. In an endoscopic surgical procedure, the distal end of a surgical instrument is inserted through small incisions in the body to access a surgical site. Typically, a appropriately sized cannula, e.g., 5 mm, 10 mm, etc., is inserted through the body incision to provide a guide channel for accessing the surgical site. Because it is desirable to provide small body incisions so that there is less scarring, reduced trauma to the patient, faster healing time, the tolerances between the surgical instrument and the inner diameter of the cannula are small.
When a surgical instrument having an articulating tool assembly is used during an endoscopic procedure, the articulating tool assembly is generally in its non-articulated position (i.e., a position in which the longitudinal axis of the tool assembly is aligned with the longitudinal axis of the body portion of the surgical instrument), during insertion of the tool assembly through a cannula or small body incision. Movement of the tool assembly to an articulated position, even slightly misaligned with the body portion of the surgical instrument, may interfere with and/or prevent insertion of the distal end of the surgical instrument through the cannula or small body incision.
During manipulation or handling of a surgical instrument having an articulating tool assembly, it is not uncommon for the tool assembly to be jarred or bumped such that the tool assembly inadvertently is moved from its non-articulated position to an articulated position. As discussed above, this is undesirable, especially where the surgical instrument is to be used in an endoscopic surgical procedure. In addition, the ability of the tool assembly to hold its position with respect to the handle portion will affect how well a surgeon can manipulate tissue using the tool assembly.